Recent findings from the Diabetes Prevention Program (DPP) have established that diabetes can be prevented, or at least delayed. Participants in the DPP all had fasting plasma glucose (FPG) levels between 95 and 125 mg/dl, below the current threshold for the diagnosis of diabetes. The American Diabetes Association recognizes an intermediate metabolic stage between normal glucose levels (FPG <110 mg/dl) and levels sufficient to define diabetes (>126 mg/dl). This intermediate stage, known as impaired fasting glucose (IFG), is a major risk factor for future diabetes. The upper range of normal FPG (95-109 mg/dl) may represent a still earlier stage of abnormal glycemia. Following the DPP, we can expect health plans and clinicians to increase efforts to delay or prevent diabetes. However, the characteristics of patients with IFG, and with high-normal FPG have not been described. In particular, we know relatively little about who ultimately develops diabetes and how quickly. Additionally, medical utilization and costs of these persons, relative to normoglycemic persons, have not been enumerated. Forecasts of cost savings of diabetes prevention will be inaccurate without accurate estimates of costs of patients with abnormal glucose. The objective of the proposed research is to explore the intermediate metabolic stage known as IFG, and also high-normal FPG, to build a knowledge base that will contribute to strategies to prevent diabetes and its complications. We propose to create a registry of patients with high-normal FPG (95-109 mg/dl) or with IFG (110-125 mg/dl), and also create an age- and gender-matched comparison group of subjects with normal FPG (<95 mg/dl). We will then describe the progression of stages of FPG, from normal to high-normal to impaired to diabetic, and estimate multivariate models to identify independent risk factors for progression across these stages. Finally, we will calculate and compare the costs of medical care for patients in each FPG stage, and estimate multivariate models to identify factors that contribute to medical costs in each stage.